There are between 14 and 16 air-filled sinus cavities in the skull. These are located on either side of the nose, behind and between the eyes, in the forehead and deeper towards the back of the skull, and are sub-categorised in four areas (see diagram below).

They make our facial bones lighter, improve voice resonance and absorb some of the impact if you receive a hard blow to the head.

Regardless of where they're situated, the sinus cavities all serve the same purpose – to humidify the air we breathe in, with the mucous layer moisturising the nose.

How does sinusitis occur?

Sinusitis occurs when the tissues lining these cavities become inflamed. The more inflamed they get, the more mucus is produced. Normally, a small amount of mucus in the cavities acts as a filter for bacteria and germs to keep them from entering the deeper respiratory tract.

But when your nasal cavities become irritated mucus production becomes excessive, leading to congestion.

It’s not only the mucus that causes that stuffy, congested feeling. When the nasal passages are inflamed, the blood vessels also swell.

And if any excess mucus runs down the back of your throat, it can lead to additional symptoms such as coughing (especially at night), a sore throat, or even nausea and digestive problems like diarrhoea.

The diagram below shows the anatomy of the nose and how the nose and throat are connected.

What causes sinusitis?

Sinusitis can be triggered by allergic reactions to environmental factors, such as pollen or pet dander, but it can also occur as the result of a cold or flu.

Sinuses can become physically obstructed by tumours or growths. Nasal polyps which can grow from the mucous surfaces in the nose, probably caused by nasal inflammation, can block the nasal cavities.

Occasionally immune problems cause chronic sinus infections. If you have persistent sinus infections, have your immune system evaluated by an allergist/immunologist, especially before you have surgery. You may need allergy tests and tests to ensure you can form antibodies to common bacteria in a normal way. In rare cases, recurring sinusitis could point to an impaired immune system as the result of a condition such as Aids.

How to relieve congestion

There are several ways to treat the symptoms of sinusitis at home, whether it’s over-the-counter or a home remedy:

Drink plenty of clear fluids, such as water or herbal tea, to thin the mucus.

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Dr Gary Kroukamp MBCHB, FCORL(SA) is an ENT Specialist, practising from rooms at Kingsbury Hospital in Claremont, Cape Town. He also has a teaching sessional appointment as an ENT Consultant at the Tygerberg Hospital. He is a member of the ENT Society of South Africa and the South African Cochlear Implantation Group. His interests in the ENT field include sinusitis and sinus surgery, nasal allergy and ENT conditions in children.

posted on 14/04/2018

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